1. Field of the Invention
This invention is related in general to the field of microscopy. In particular, it relates to automated mechanisms to feed slides to a microscope from a removable slide magazine.
2. Description of the Related Art
In pathology and other biomedical practices, a sample is removed from a patient and fixed to a glass slide for staining and microscopic examination. For example, the morphology of the sample is analyzed to provide a qualitative assessment of its condition and to identify the presence of pathologic changes, such as may indicate progression towards a malignancy. For many decades, this visual procedure has been the diagnostic mainstay of pathology.
With the advent of computers and sophisticated digital imaging equipment, researchers have extended the realm of these analytical procedures through the use of mechanized instrumentation for diagnostic and quantitative investigation. In such mechanized procedures, the samples are imaged with a microscope and the images are digitized, stored, and analyzed (so called “virtual slide technology”). Historically, the slides have been stored in horizontal trays that hold 4 to 20 slides. During the process of retrieval and imaging in the microscope, the slides are handled manually.
As digital imaging gains more and more acceptance among pathologists and in laboratories for the purposes of diagnosis, archiving, and telepathology, the transition from conventional to digital procedures is producing a strong need for high throughput in slide digitization. Therefore, an important aspect of the economic viability of virtual slide technology is the ability to process a large number of slides in a short time. The rapid scanning times of ever-improving microscopes need to be accompanied by correspondingly faster and faster automatic slide loading and unloading systems.
Typical slide feeders for projectors and other optical instruments consist of mechanical devices adapted to receive a slide tray or magazine and sequentially retrieve each slide from its slot in the tray or magazine, place the slide on the stage of the instrument for processing, and return the slide to its slot in the tray or magazine. In the field of biomedical imaging, the state of the art consists of a slide loader wherein a tray of slides is first retrieved with a mechanical arm from a stack of trays housed in a library. A slide is lifted with a suction cup from the tray, placed on a microscope stage for processing, and returned to the tray for storage. By sequentially loading and unloading slides from the various trays, the instrument is capable of processing in excess of 100 slides per hour automatically. Such a system is currently sold by Vision Systems Limited of Mount Waverley, Australia, as the SL50 Automated Slide Loader.
While this recent robotic improvement of conventional “pick and place” technology has accelerated the ability to process slides, its performance is limited by the fact that each tray must be removed from a stack prior to retrieval of the slide of interest. In addition, either the tray or the slide needs to be moved vertically for alignment with the elevation of the sample stage. Very sophisticated and relatively cumbersome mechanisms are required to perform such multi-step functions, which is expensive to implement and limits the ability to achieve even greater throughputs. This invention provides a general and efficient solution toward that end.